Carbonation reactivity of wollastonite enhanced by incorporating sodium-based alkali additives

The carbonation of wollastonite presents a promising approach for CO 2 sequestration and the development of sustainable cementitious materials. This study investigates the enhancement of wollastonite carbonation through the incorporation of sodium-based additives (Na 2 CO 3 and NaHCO 3 ) under carbonation curing conditions. X-ray diffraction analysis revealed that increasing the dosage of Na₂CO₃ and NaHCO₃ facilitated wollastonite dissolution and promoted calcite formation. Thermogravimetric analysis confirmed that bound CO 2 content was significantly high in carbonated samples, especially when containing NaHCO 3 at dosages of 3%. Thermodynamic modeling further indicated that wollastonite carbonation led to the formation of calcium-silicate-hydrate alongside minor phases such as magnesium-silicate-hydrate and hydrotalcite. These findings suggest that sodium-based alkali additives are an effective promoter of wollastonite dissolution and carbonation, enhancing CO 2 sequestration efficiency and contributing to the development of low-carbon cementitious materials. • Sodium-based additives (Na 2 CO 3 and NaHCO 3 ) enhance wollastonite carbonation reactivity. • NaHCO 3 is more effective than Na 2 CO 3 in promoting wollastonite dissolution. • A 3% NaHCO 3 dosage yields the highest CO 2 uptake. • Calcite and C-S-H are the main products of accelerated wollastonite carbonation. • Thermodynamic modeling confirms increased C-S-H and calcite with additives.